1. Field of the Invention
The present invention relates to a catalytic converter unit for use in combination with an oven for treating odiferous emissions that may occur during a cooking event. The present invention further relates to a correspondingly equipped oven, as well as certain methodology for enhancing the efficiency of emission treatment.
2. Description of Related Art
In today's closed up and environmentally controlled houses it is not always desirable to be able to smell the resulting odors from foods being cooked in a residential oven. Certain foods, fish for example emit certain amine compounds that are noisome while greasy foods such as bacon or other high fat meats emit odors that may initially be acceptable, but impart a rancid like impression as they linger in the air. Some of the more pertinent prior art relating to means for treating cooking emissions, including ovens having catalytic conversion units and the like are briefly described hereinafter.
U. S. Pat. No. 2,862,095 ('095 Patent), which issued to Scofield, discloses certain Vapor Treating Means. The '095 Patent teaches certain hardware usable in combination with an oven compartment forming part of a domestic cooking range and having a substantially open front and a door for substantially closing said front, which door partially seals the front when closed. The hardware comprises heating equipment for the compartment; a vapor passage having an inlet and an outlet in the compartment; vapor purifying means is said passage; a vent arranged for venting purified vapor from the passage into the ambient atmosphere; a vapor blower for moving vapor from the compartment through the passage and through the vapor purifying means therein to said vent and also back to the compartment; means for simultaneously controlling the degree of opening of the vent and the degree of heating provided by the heating equipment; and means associated with said passage for lowering the pressure of circulated vapor, inside the compartment, below the normal pressure of the ambient atmosphere at all degrees of opening of the vent.
U.S. Pat. No. 3,785,778 ('778 Patent), which issued to Burstein et al, discloses a Smoke Eliminating Device. The '778 Patent teaches a device for eliminating combustible, carbon containing vapors or smoke comprising a device having an inlet hood capable of collecting smoke from a broiler or other cooker. The device has an outlet and a passageway between the hood and the outlet. In this passageway is a cellular, catalyst-coated refractory block threaded with high resistance electrical wire for heating the block cells. An impeller associated with the passageway draws the vapors through the heated block cells for combustion of the vapors and then forces them on through the outlet.
U.S. Pat. No. 4,039,292 ('292 Patent), which issued to Morini et al, discloses a Catalytic Converter for Oven Fumes. The '292 Patent teaches a catalytic oxidation unit of the type used for oxidizing fumes from ovens and the like comprising a metallic housing providing a tubular body portion with spaced shoulders in the through passage and a block of cellular ceramic material therebetween. One of the spaced shoulders is provided by an apertured front wall on the housing, and the block of ceramic material is biased against this front wall shoulder by resiliently compressible means acting between the block and the other shoulder. The ceramic material block has an oxidation catalyst on the walls of the cells thereof which is effective to oxidize organic materials in the fumes passing through the metallic housing and the block of ceramic material therewithin.
U.S. Pat. No. 4,089,088 ('088 Patent), which issued to Konczalski, discloses a Thermal Regeneration and Decontamination Apparatus and Industrial Oven. The '088 Patent teaches an air-permeable reactor medium of large surface area and high thermal capacity, coated with a catalyst, is cycled along a closed path across a first duct carrying an air stream laden with oxidizable contaminants and a second duct carrying a stream of fresh air, enabling contaminants in the first air stream to be oxidized to innoucuous byproducts, releasing heat which is transferred to the fresh air in the second duct, the reaction medium moving at a variable speed which is a function of the temperature of one of the air streams; considerable improvement in the efficiency of an industrial oven may therefore be achieved by positioning the reactor medium to exchange heat between an incoming stream of fresh air and a stream of hotter exhaust gas so that the temperature of fresh air delivered elsewhere to the oven may be controlled without having to rely on dampers and mixtures of air volumes with inherent damper malfunctions or mis-metering; also a second burner may be eliminated because of the manner in which the reactor medium is utilized to exchange heat.
U.S. Pat. No. 4,138,220 ('220 Patent), which issued to Davies et al, discloses an Apparatus for Catalytic Oxidation of Grease and Fats in Low Temperature Fumes. The '220 Patent teaches a method and apparatus for catalytically oxidating grease, fats, oils and/or other hydrocarbons in fumes rising from a source thereof. In particular, grease and odor-laden air streams, i.e. hydrocarbon-laden air streams, emanating from a source such as a cooking grill or the like are heated to a temperature at which passage over a catalyst causes flameless oxidation of the organic material in the air stream at a temperature below combustion temperature, the organic material being converted essentially to carbon dioxide and water, with release of at least some heat energy. The oxidized and heated air stream is ducted in countercurrent relation or in identically parallel direction, to the relatively cooler hydrocarbon-laden air stream which is being ducted toward the catalyst, heat exchange from the oxidized air stream to the hydrocarbon-laden air stream thereby occurring to at least partially heat the hydrocarbon-laden air stream. Additional heat energy can also be introduced if necessary into the unoxidized air stream prior to passage over the catalyst in order to raise the temperature of the airstream to the operating temperature of the catalyst.
U.S. Pat. No. 4,330,503 ('503 Patent), which issued to Allaire et al, discloses a Wood Burning Stove. The '503 Patent teaches an improved wood burning stove employing a combustion chamber and a flue for removing exhaust therefrom and also a catalytic converter means for oxidizing oxidizable species in the exhaust. A passageway is provided for bypassing the exhaust around the catalytic converter means, the passageway being controlled by a bypass damper for controlling access to the passageway for varying impedance otherwise presented to the exhaust by the converter, for example, during the addition of fuel to the stove. Such an arrangement minimizes back pressure caused by the converter means.
U.S. Pat. No. 4,654,508 ('508 Patent), which issued to Logel et al, discloses an Electro-Domestic Oven having a Catalytic Reactor with a Depression Baffle. The '508 Patent teaches an electric domestic oven comprising an air exhaust channel above the exit from a catalytic reactor. A depression baffle is located in the air exhaust channel to provide a suction orifice in the area of the catalyser unit to draw cooling and cleaning gases from the cooking compartment. The depression baffle has a curved upstream portion and a ramp-shaped downstream portion. A deflector may be placed above the baffle in the channel.
U.S. Pat. No. 4,831,237 ('237 Patent), which issued to Gelineau, discloses a Cooking Oven with Self-Cleaning Pyrolysis System. The '237 Patent teaches an electric oven with self-cleaning pyrolytic system, includes a catalyst for smoke or fumes, at least one vault resistance and one sole resistance of standard values, wherein the oven further comprises means for powering at the beginning of a pyrolysis operation, simultaneously and exclusively the vault resistance and a part of the sole resistance, so that the power supplied by this part of the sole resistance is lower than the power supplied by the vault resistance, and wherein the catalyst is produced from a material that allows its activation prior to the saturation of the oven by smoke or fumes, exclusively through the convection heat passing into a pipe housing the catalyst from the oven, and wherein means are provided for powering other resistances after the beginning of activation of the catalyst, in order to reach the pyrolysis temperature.
U.S. Pat. No. 5,927,265 ('265 Patent), which issued to McKee et al, discloses a Recycling Cooking Oven with Catalytic Converter. The '265 Patent teaches a recycling cooking oven providing a substantially closed environment. The oven includes a thermal plenum for supplying a stream of hot air into a cooking chamber and for receiving a stream of hot air from the cooking chamber, the thermal plenum maintaining a reservoir of hot air therein. The cooking chamber of the oven supplies a stream of hot air into the thermal plenum and receives a stream of hot air from the thermal plenum, the cooking chamber cooking foods therein at least partially with a stream of hot air and such foods adding oxidizable components to the hot air of the stream. A blower and ducting cause the stream of hot air to circulate in substantially a continuous travel path including the thermal plenum and the cooking chamber. A catalytic converter is disposed in the travel path of the stream of hot air, downstream of the cooking chamber and upstream of the thermal plenum, for flamelessly oxidizing oxidizable components in the hot air of the stream leaving the cooking chamber, thereby both to remove them from the hot air of the stream and to release at least some additional heat energy into the hot air of the stream.
U.S. Pat. No. 6,058,924 ('924 Patent), which issued to Pool, III et al., discloses a Vented Recycling Oven with Separate Catalytic Converter. The '924 Patent teaches a recycling cooking oven for cooking food at least in part by hot air flow and providing a substantially closed but vented environment includes a cooking chamber for receiving a stream of hot air from an upstream thermal plenum via a plurality of openings in the cooking chamber, the cooking chamber cooking food therein at least partially with hot air from the plurality of openings and the cooking of such foods adding oxidizable components to the hot air. A blower circulates the stream of hot air in substantially a continuous travel path including the thermal plenum, the plurality of openings and the cooking chamber. A main catalytic converter is disposed in the continuous travel path for flamelessly oxidizing the oxidizable components leaving the cooking chamber. A vent communicating with ambient atmosphere and the main catalytic converter diverts an auxiliary vent stream of hot air from the main catalytic converter into the vent; and an auxiliary catalytic converter is disposed in the vent, downstream of the main catalytic converter, for flamelessly oxidizing oxidizable components in the hot air of the auxiliary vent stream passing through the vent, thereby to further remove oxidizable components from the hot air of the auxiliary vent stream and so release a relatively clean auxiliary vent stream of hot air from the vent into the ambient atmosphere.
U.S. Pat. No. 6,131,559 ('559 Patent), which issued to Norris et al, discloses a Convection Oven with Smoke Management Means. The '559 Patent teaches a convection heating apparatus with smoke and grease management means and an improved temperature controlled gas delivery system. The apparatus includes an exterior cabinet, an interior chamber and intermediate walls disposed between the exterior cabinet and interior chamber such that an intermediate cavity is provided between the interior chamber and intermediate walls and an outer cavity is provided between the exterior cabinet and intermediate walls. The apparatus further includes a product support, preferably a conveyor, disposed in the interior chamber. A blower for circulating temperature controlled gas into said interior chamber is also provided which is in fluid communication with at least one duct (preferably a plurality) having a jet plate with orifices positioned to direct temperature controlled gas toward the product support. A second blower is provided for circulating air through the outer cavity and intermediate cavity to cool the exterior cabinet walls and interior chamber walls. An improved air delivery duct is provided having a dual taper resulting in uniform distribution of the temperature controlled gas to a food product. An air filtering system is also provided comprising a perforated filter plate or louvers and/or catalytic converter disposed in the temperature controlled gas return path.
U.S. Pat. No. 6,437,294 ('294 Patent), which issued Allera et al., discloses a Pyrolytic Self-Cleaning Oven. The '294 Patent teaches a pyrolytic self-cleaning oven having a catalytic composition positioned in the oven cavity or exhaust gas passage in order to complete the combustion and/or the oxidation of gases produced by a process carried out inside the oven. The catalytic composition is supported by a ceramic coating on a metal wire. The metal wire is electrically connected to a control system of the oven for controlling the cooking and/or pyrolytic cleaning process. The catalytic composition carried on the metal wire may be part of a net-shaped catalytic element.
U.S. Pat. No. 6,780,225 ('225 Patent), which issued to Shaw et al, discloses a Reflow Oven Gas Management System and Method. The '225 Patent teaches a reflow solder oven gas management system which introduces an inert gas into and removes contaminated gas from a reflow oven tunnel (42) at predetermined points (6, 8) to influence the oven tunnel gas flow and to dilute and expel excess oxygen. The contaminated gas is ducted to a flux separation system (34) to be cleaned, for example remove flux vapors, and returned in part to the tunnel (42) for recirculation and with the remainder routed to end baffle boxes (54) for tunnel end pressurization and exhaust. The system has sufficient pressure to supply end baffle boxes (54) with clean gas to create a gas barrier to effectively seal off the tunnel ends from air infiltration or migration into the tunnel making the system insensitive to external pressure and/or temperature variations. The invention also includes alternative embodiments, low flow oxygen bleed valves (72) to maintain low oxygen content in the oven process tunnel.
United States Patent Application Publication Number US 2002/0059930, which was authored by Schmidmayer et al, describes a catalytic converter for use in an oven comprising at least two sub-catalysts connected in series. One of the sub-catalysts includes a catalytically active metal layer as its active surface to improve the efficiency of the catalytic converter with respect to the elimination of unpleasant odors. The one sub-catalyst includes a metal oxide as its active surface. At least one other sub-catalyst includes, as its active surface, a metal layer selected from elements in groups 8 to 10 of the periodic table.